Optical head device with multiple diffracting planes, and an optical information apparatus, computer, video recording/reproducing apparatus, video reproducing apparatus, server, and car navigation system including the same
a technology of optical head and diffracting plane, which is applied in the direction of optical beam sources, television systems, instruments, etc., can solve the problems of deteriorating recording/reproducing properties, unable to obtain a tracking error signal in good conditions by a general 3-beam tracking system, etc., and achieves stable recording and/or reproducing operation
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embodiment 1
[0066]FIG. 1 is a diagram showing an optical head device 100 in Embodiment 1 of the invention. The optical head device 100 performs recording and / or reproducing of information to and / or from an optical recording medium 7 by irradiating the optical recording medium 7 with laser light. The optical head device 100 includes a light source 1, a diffraction element 2, a polarizing beam splitter 3, a collimator lens 4, a quarter-wave plate 5, an objective lens 6, a detection lens 8, a photo detector 9, and a photo detector 10 for controlling the quantity of light of the light source.
[0067]The light source 1 is a dual-wavelength light source in which two light emitting elements 1a and 1b with mutually different emitting wavelengths are mounted in one module. For example, the light emitting element 1a emits one of coherent light with wavelengths of 640 nm to 680 nm and coherent light with wavelengths of 760 nm to 800 nm. The light emitting element 1b emits the other light. The light emitting...
embodiment 2
[0111]In an optical head device 100 of this embodiment, a light source 1 is a three-wavelength light source in which, in addition to light emitting elements 1a and 1b, a light emitting element 1c is mounted, as shown in FIG. 7B. The light emitting element 1c emits coherent light with wavelengths of 390 nm to 430 nm, for example. The light emitting elements 1a to 1c are disposed along a direction corresponding to a radial direction of an optical recording medium 7.
[0112]For the light with wavelengths of 390 nm to 430 nm, a polarizing beam splitter 3 transmits 90% and reflects 10% of certain linearly polarized light. The polarizing beam splitter 3 reflects 100% of linearly polarized light which is diagonal to the polarizing direction of the certain linearly polarized light. On a surface of an objective lens 6, a diffraction grating is formed so that the numerical aperture (NA) for the light with wavelengths of 390 nm to 430 nm is 0.85.
[0113]Next, a diffraction element 2 in this embodi...
embodiment 3
[0125]FIG. 8 is a diagram showing an optical information apparatus 80 in Embodiment 3 according to the invention. The optical information apparatus 80 performs recording and / or reproducing of information to and / or from an optical recording medium 7.
[0126]The optical information apparatus 80 includes an optical head device 100, a motor 82, an electric circuit 83, a turning table 84, a cramping circuit 85, and a driving unit 86 for the optical head device. The optical head device 100 is the same as the optical head device 100 described in Embodiments 1 and 2. The electric circuit 83 functions as a control unit for controlling operations of the optical head device 100 and the other components.
[0127]The optical recording medium 7 is put on the turning table 84, and turned by the motor 82. The optical head device 100 is moved to a track position of the optical recording medium 7 in which desired information is recorded by means of the driving unit 86.
[0128]The optical head device 100 tra...
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Abstract
Description
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